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Geometry Monitoring System

Geometry Monitoring System. Present status (TDR) and difficulties The RELCAM sensor (TDR) The RASNIK alternative A realistic RASNIK segment Equations to be solved Ongoing work Project plan. Present difficulties. In TDR, the set-up of laser lines is:

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Geometry Monitoring System

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  1. Geometry Monitoring System • Present status (TDR) and difficulties • The RELCAM sensor (TDR) • The RASNIK alternative • A realistic RASNIK segment • Equations to be solved • Ongoing work • Project plan gms, jyg, mont dore 2002

  2. Present difficulties • In TDR, the set-up of laser lines is: • 4 lines in two vertical planes and one step • 4 lines in 45o planes in azimuth and two steps • Problems of this set-up are: • No projectivity • Two supports to be monitored … induce lost of precision • Effect of temperature gradient expected important in this case of long light lines … question about realistic shielding gms, jyg, mont dore 2002

  3. The RELCAM sensor • In TDR, was presented the RELCAM sensor: • Semi-reflecting mirror • CMOS camera (628 x 582 pixels) • Test on bench • Laser (785 nm), Granit table (2.5 x 0.5 m2) • Motorized stage (x, y) … ±0.5 μm • Results: • Resolution: σx = σy = 0.5 μm • Stability: Δx, Δy < 0.8 μm per oC • Linearity: < 1 μm within 2 x 2 cm2 • Problem: a 2 dimension sensor in the transverse directions (x, y) • z direction not monitored gms, jyg, mont dore 2002

  4. One step laser lines • We cannot adopt such a set-up • Due to the constraints imposed by the coil • More than 24 slats of the stations 3, 4, 5 would be on the path of the lines • No realistic change in their design is possible … without triggering a crisis with Manoel and others • Need of new system for monitoring gms, jyg, mont dore 2002

  5. Alternative proposal • Based on the RASNIK sensor • Each element is set on a chamber frame/support to be monitored • Resolution: σx = σy = 1 μm,σz = 100 μm • Well adapted to our problem • Used byL3, adopted by (GEM) and ATLAS • Advantages: it is a 3 dimension sensor … and no laser beam is used (safety) gms, jyg, mont dore 2002

  6. A realistic RASNIK segment • Initial positions of the Mask and Camera not on the Lens axis • Initial recorded Mask image is not centered on the Mask • x M,L,C, yM,L,C, zM,L,C shifts can be extracted from the analysis of the final Mask image gms, jyg, mont dore 2002

  7. The recorded images y 16 pads x M 25 pads 25 pads gms, jyg, mont dore 2002

  8. Equations to be solved • x0 (y0): initial distance between the camera and the plane xOz (yOz) containing the optical axis of the lens • δ (δ’): initial Mask-Lens distance (Camera-Lens) along the optical axis • The displacements of the RASNIK elements (Mask, Lens, Camera) in their coordinate systems are:xM, yM, zM, xL, yL, zL, xC, yC, zC • Few RASNIK lines are necessary for the monotoring of three planes … if these planes are rigid planes • x, y: shifts of the image • M: magnification x y M (Philippe Pillot) gms, jyg, mont dore 2002

  9. Proposal for a new set-up Reference plane • We propose to study the performance of a monitoring system with: • 8 RASNIK segments on: the muon filter (C), the chamber 10 (L), the chamber 9 (M) • Then, 8 RASNIK segments on: the chamber 10 (C), the chamber 8 (L), the chamber 6 (M), the chamber 6 (C), the chamber 4 (L), the chamber 2 (M), the chamber 9 (C), the chamber 7 (L), the chamber 5 (M), and the chamber 5 (C), the chamber 3 (L), the chamber 1 (M) • And, to increase the constraints between the two groups of chambers, 8 RASNIK segments on: the chambers 2 (C), the chamber 1 (L and M), and the chamber 4 (C), the chamber 3 (L and M) gms, jyg, mont dore 2002

  10. Present work • Evaluation of the performances of the proposed setup • Resolution in position of each chamber • Resolution in mass at the Υ mass • Localization of the monitoring lines through the spectrometer • Position of the elements on the chamber frames/supports … in collaboration with the Engineers • Decision (?) for a monitoring of the chamber/support flatness • Choice of the system, position of the elements … in collaboration with the Engineers • Alternative to RASNIK (?) • System baseline design to be decided by June 2002(?) gms, jyg, mont dore 2002

  11. Project plan • Development of the system starting as soon as possible in 2002 • Measure of the performances • Study of the temperature gradient effects (neutralization) • Technical support demanded, answer expected soon • Realisation of the system starting in 2004 • Design study • Fabrication of sensors and supports • Calibrations • Installation • Lyon and Erevan • Budget (MOU) • 140 KFS to be re-estimated gms, jyg, mont dore 2002

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